1. Technical Field
The present invention relates to a vehicle seat belt retractor having a spool on which seat belt webbing is wound. The spool can be blocked from rotation in the belt withdrawal direction either (i) in response to acceleration of the spool in the belt withdrawal direction at a rate above a predetermined rate or (ii) in response to deceleration of the vehicle at a rate above a predetermined rate. The retractor is thus both web sensitive and vehicle sensitive.
2. Description of the Prior Art
U.S. Pat. No. 4,422,594 discloses a retractor which is both web sensitive and vehicle sensitive. Upon sudden vehicle deceleration, a vehicle sensitive inertia member pivots a sensor lever. The sensor lever moves an operating lever into engagement with an external tooth on a support member which rotates with the spool. The operating lever is carried by a locking pawl actuator. Rotation of the support member then results in the locking pawl actuator being rotated. When the locking pawl actuator rotates, it moves a locking pawl into engagement with ratchets fixed to the spool, thus blocking rotation of the spool in the belt withdrawal direction. Upon rapid belt withdrawal from the spool, a web sensitive inertia sensor pivots into engagement with an internal tooth on the locking pawl actuator. The web sensitive inertia sensor is pivotally mounted on the rotating support member. Rotation of the support member when the web sensitive inertia sensor is in engagement with an internal tooth on the locking pawl actuator results in the locking pawl actuator rotating. When the locking pawl actuator rotates, the locking pawl is moved into engagement with the ratchets to block rotation of the spool in the belt withdrawal direction.
U.S. Pat. No. 4,452,405 also discloses a retractor which is both web sensitive and vehicle sensitive. Upon sudden vehicle deceleration, a vehicle sensitive inertia member pivots a sensor lever carried by a locking pawl actuator into engagement with an external tooth on a control gear which rotates with the spool. Rotation of the control gear then causes rotation of the locking pawl actuator which moves a locking pawl into engagement with a ratchet fixed to the spool, thereby blocking rotation of the spool in the belt withdrawal direction. Upon rapid belt withdrawal from the spool, a flywheel rotates relative to the control gear. Relative rotation of the control gear and flywheel pivots a control pawl carried by the control gear into engagement with an internal tooth on the locking pawl actuator. Thereafter, rotation of the spool causes the control gear and locking pawl actuator to rotate to move the locking pawl into engagement with the ratchet, thereby blocking rotation of the spool in the belt withdrawal direction.